Switch



Aug 5, 1941 I s BEAR ETAL I I 2,251,316

SWITCH Filed May 22, 1939 INVENTORS. flaw 555%, 61584415 575023,

BY ATTORNEY. A

Patented Aug. 5, 1941 SWITCH Paul S. Bear and Gerald E. Spates, Elkhart, Ind assignors to Bucklen-Bear Laboratories, Inc., Elkhart, Ind., a corporation of Indiana Application May 22, 1939, Serial No. 274,876

7 Claims.

One of the primary objects of the present invention is to provide a metal envelope mercury switch which is symmetric about its longitudinal axis, and is adapted to be mounted in a vertical position in such manner that tilting of the switch axis in any direction from the vertical position will result in moving it from one circuit controllingposition to another. Such switches are especially adapted for use as safety switches in vehicles for breaking the ignition circuit and the lighting circuit in theevent of overturning of the vehicle, thus eliminating the possibility of fire or explosion.

One of the features of the present invention is the use of an insulating material which serves as a centering means for one electrode of the switch, and which is sealed in position along with the electrodes by means of suitable sealing means which allows evacuation of the switch and filling of the same with a gas or liquid providing a reducing atmosphere, as desired.

Still another object of the present invention resides in the provision of a switch structure which is easy to assemble, compact in form, and readily capable of being mounted in any suitable operating position, and which is low in cost.

Other objects and advantages of thepresent invention will appear more fully from the following detailed description which, taken inconjunction with the accompanying drawing, will disclose to those skilled in the art the particular construction and operation of a preferred form of the present invention.

In the drawing:

Figure 1 is a vertical sectional view'through one form of switch embodying the present invention; and i Figure 2 is a similar view of a modified form of switch.

Considering now Figure 1 in detail, this switch.

embodies a metal envelope indicated generally at 5 having the substantially hemispherical cup-- jecting therefrom and of a slightly increased diameter, thereby forming the radial shoulder B therebetween.

Disposed in abutment against the shoulder 8 is an insulating member 9 which may be made of a refractory material, such as a ceramic or the like, and which has a substantially spherical recess Ill formed therein and forming with the internal surface of the cup portion 6 of the envelope a substantially spherical chamber within the switch.

The ceramic insulating member 9 has an opening therethrough adapted to receive the head l2 of an electrode stud l3 projecting axially thereinto, the stud l3 projecting beyond the end of the cylindrical portion 1 of the envelope and being threaded adjacent its outer end.

Disposed on the outer face of the ceramic 9 and engaging the back surface of the electrode head i2 is a resilient insulating gasket M which has an annular flange portion l5 adapted to seat in the recessed portion ll. of the ceramic 9 whereby axial compression on the member l4 results in sealing the electrode with respect to the ceramic, and also sealing the ceramic with respect to the shell portion. 7. Disposed outwardly of the gasket l4 and centered on the shank l3 of the electrode is a compression member [5 which may be formed of refractory material such as ceramic, porcelain, or the like, and which has axial flanged engagement with the outer surface of the gasket l4, whereby axial pressure thereon will compress the gasket into sealing position. Disposed against the outer radial surface of the compression member [5 is a retaining ring it formed of metal or the like, which is adapted to be engaged by the spun-over end ll of the cylindrical portion 1 of the envelope to effect compression on the member l5 and thereby trans mit this pressure to the gasket. The metal end of the envelope is spun over the retaining ring it, while the parts are compressed in position, as described in detail in the copending application of Paul S. Bear, Serial No. 211,420, filed June 2, 1938, and when spun over, provides a sealed envelope preventing the escape of any gases, either intgoor out of the chamber indicated generally at The compression member l5 has a reduced axially extending shoulder portion it which acts as an insulating spacer between the ring l6, the spun-over end ll, and the shank of the electrode l 3. The electrode is secured in position by means of the nut l9 threaded thereover, and any suitable terminal lug may be secured to the end of the electrode and a corresponding terminal lug secured to the envelope '5 providing the terminals for the switch which may thereby be connected into any desired circuit. 7

In Figure 2 an inverted form of switch is shown having slight changes in its construction. The switch envelope 5 of this form of the invention is substantially identical with the envelope 5 of Figure 1, and corresponding parts are indicated with corresponding reference numerals. Disposed within the envelope is the ceramic 9 having the spherical surface completing the semispherical surface of the portion 6 of the envelope and picked up by the resilient sealing gasket M in the same manner. A corresponding compression member i is also provided disposed beneath the retaining ring 16 which is engaged by the spun-over edge ll of the envelope. In this embodiment of the invention the electrode comprises a stud member which has the projecting end 26 extending down to a point adjacent the lower end of the envelopeii and having an enlarged portion threaded to receive the nut 21 for locking the stud 25 against outward movement. At its opposite end the stud 25 is also threaded, as indicated at 28, to receive the nut 29 clamping the same against the compression member 55, and thereby locking the stud against longitudinal movement.- The end 26 of the electrode may be a nickel alloy providing a mercury-to-mercury contact since this material has the characteristic of being wet by mercury.

Suitable insulating washers 30 are interposed between the compression member and a terminal lug member 32 secured to the stud 25 by means of the nut 29. A corresponding terminal lug member 33 is soldered or otherwise bonded to the spun-over edge ll of the envelope 5 to form the terminals for the switch. It is to be understood that corresponding terminal lug members a may be employed to the switch shown in Figure l in the same manner.

Considering again the disclosure of Figure 1,

it will be noted that there is a body of mercury 59 provided in the chamber-2i}, which body ofmercury has disposed over the surface thereofa thin film 42 of an anhydrous alkaline liquid, such as triethanolamine, having the property of increasing the meniscus height of the mercury and also preventing oxidation of the mercury, as well as forming a floatation medium for impurities found within theswitch envelope. The envelope 5 of Figure 1 may be assembled with the parts in position and under compression by spinning over the end H, and the body of mercury 30 may then be introduced into the chamber 20 through the opening 43 on the upper end of the shell 5. After being thus introduced, the liquid film is introduced on top of the mercury and the chamber may then be suitably evacuated and then sealed by means of the sealing plug at having a tapered seat or threaded seat in the opening 83. If desired, hydrogen or a similar reducing gas under pressure may be introduced into the chamber through the opening 13 to drive out all possible air or the like, and may then be sealed in the chamber under such pressure to form a reducing atmosphere in the chamber.

It will be apparent that upon tilting of the switch from its vertical position, the body of mercury will move into a position forming a bridging contact between the electrode head I2 and the chamber wall 6, thereby completing the circuit through the switch, and upon return of the switch to its normal vertical position, the 75 circuit will be broken across the surface of the insulating member 9. Thus, this form of switch provides a construction which is normally in switch open position, but which, upon tilting, moves into switch closing position for closing the circuit therethrough. Such a switch may be used for grounding the ignition and power circuits of a vehicle or the like in case of overturning.

In the form of switch shown in Figure 2, the body of mercury 59 in this form of switch has a similar liquid film 52 thereover, but is of sulficient volume so that it provides contact between the end portion of the stud 26 and the internal surface of the cup-like portion 3 of the envelope, To fill this type of switch, we preferably provide a tubular member 53 which is inserted from the internal side of the shell 6 outwardly through an opening 54 formed in the end thereof, and is provided with a substantially radial flange portion 55 which may be welded or otherwise securely sealed to the internal surface of the switch. The mercury and liquid '52 may be in troduced through this tubulation and after the interior oi the switch chamber has been evacuated or has been filled with a reducing atmosphere, the. tubulation is pinched together as indicated at 56 to seal the envelope, and may then be welded to provide a permanent seal.

With this form of switch the circuit is normally closed between the electrode and the envelope, but tilting of the switch a predetermined amount from its vertical position will result in movement of the body of mercury 59 along the ishell 6 to a position where it no longer contacts the end of the stud 26, and consequently breaks the circuit through the switch. Such a switch may be interposed directly in the ignition and lighting circuits of a vehicle, and upon overturning of the vehicle, will open the circuit from the battery to any portion of the power circuit.

It is to be understood that by overturning is meant the tilting of the vehicle beyond a predetermined amount in any direction, and is not limited to a complete overturning of the vehicle since movement of approximately 45 degrees of the switch out of its vertical position will result in such changing of its circuit controlling posii tion.

The liquid film t2 employed inthese switches is a heavy viscous type liquid, and has an appreciable effect in dampening the movement of the mercury due to vibration or small jolts or shocks, and prevents any breaking of the circuit fore do not intend to be limited except "as defined by the scope and spirit of the appended claims.

We claim: 1. A switch comprising a drawn metal shell having a hemispherical chamber portion and a cylindrical open end joined to the edge of said portion by a radial shoulder, an insulating support having a hemispherical recess opening toward said corresponding shell portion and abutting against shoulder sealed in the open end 'of said shell, electrode'means in said support and projecting therebeyond into said shell, and a body of mercury in said shell in contact with said electrode means when said switch is in vertical position, but adapted to move out of contact with said electrode means upon predetermined tilting of the switch in any direction from its vertical axis.

2. A safety switch comprising a hemispherical metal envelope having an enlarged cylindrical end joined thereto by an integral radial shoulder, a ceramic in said end abutting against said shoulder, an electrode carried by said ceramic having a shank projecting axially out of said end of said envelope, said ceramic having a hemispherical recess therein facing said envelope with the electrode head centered in said recess, sealing means in said end, and a body of mercury in said recess sufficient to bridge across said recessed portion of said ceramic from said electrode to said envelope when said switch is tilted from a normal vertical positionthrough a predetermined angle.

3. A switch comprising a cup-like metal envelope having a cylindrical open end, an insulating body centered in said end and having a corresponding cup-shaped recess in the inner face thereof defining with said envelope a spherically shaped switch chamber, an electrode supported in said body and having an outwardly projecting terminal portion, means sealing said body in said end of said envelope, said electrode having means projecting inwardly through said chamber toward the closed end of said envelope, and a body of mercury in said chamber normally bridging between said projecting means and said envelope, and adapted to break contact therebetween upon tilting of said switch beyond a predetermined angle.

4. A switch comprising a hemispherical metal envelope having a cylindrical open end and including means forming a radial shoulder therebetween, an insulating body centered in said end in abutment with said shoulder and sealed with respect to said envelope, an electrode projecting through said body to a point adjacent the base of the envelope and sealed with respect to said body, a body of mercury in the base of said envelope normally bridging between said electrode and envelope when the switch is in vertical position with the open end of the envelope uppermost, but adapted to break contact therebetween upon tilting of the switch beyond a predetermined angle irom the vertical,

5, In combination, a metal shell having a hemispherical portion terminating in an enlarged cylindrical end, a ceramic seated on the edge of said hemispherical portion and having a corresponding recess defining with the shell a substantially spherical switch chamber, an electrode having a contact portion projecting through the ceramic into said chamber and having an outwardly projecting shank, means on said contact portion engaging the inner face of said ceramic to axially adjust the position of said contact portion relative to said hemispherical portion, resilient means sealing said electrode and ceramic in said enlarged end of said shell, and a body of mercury in said chamber adapted to make and break contact between said shell and electrode upon tilting of said switch.

6. A metal envelope switch comprising a hemispherical shell having an enlarged cylindrical end joined to the periphery thereof by a radially inturned shoulder, a ceramic seated against said shoulder and having a hemispherical recess therein facing said shell, an electrode centered in said recess, a body of mercury in said shell adapted to bridge between said shell and said electrode when the switch is in one position, and a tubulation projecting from the lower end of said shell and welded thereto for evacuating the shell, said tubulation being pinched and welded to seal the interior of the shell after evacuation.

'7. In a metal envelope type mercury switch, a hemispherical shell portion having a radially enlarged cylindrical flange joined to the defining edge of said shell portion by a radial flange, a ceramic insert seated in said flange against said shoulder and having a hemispherical recess forming with said shell portion a spherical switch chamber, said insert having an axial cylindrical bore therethrough, an electrode having a cylindrical head fitted in said bore and an outwardly projecting shank, resilient sealing means engaging the outer faces of said electrode head and insert, compression means engaged by a spun over edge of said flange for holding said sealing means in sealing engagement with said faces, and a body of mercury lying in said recess in engagement with said electrode head and adapted to bridge across said insert to said shell upon tilting of said switch through a predetermined angle.

PAUL S. BEAR. GERALD E. SPATES. 

